The application of heat by means of water is perhaps more commonly practised for therapeutic reasons than even an application of cold. Almost all severe pains in the organs of the body are more or less alleviated by the hot-water bag. Especially is this true of abdominal pains. The alleviation which is secured by the application of the hot-water bag is well marked in many of these painful attacks. The dilatation of the vessels, the increased activity produced by the warmth and the general stimulation of the superficial parts to which the heat is applied, all tend to promote favorable healing action in many congested and pain-racked parts.

•It must not be forgotten that there is a very general depressing effect produced by too extensive or too long-continued appliaction of heat. One may remain in the Turkish bath surrounded by steam at a temperature considerably above that of the blood for 10 or 15 or 20 minutes, or even longer in some cases, without being notably depressed. Sooner or later, however, a feeling of oppression and weakness supervenes, which is an index that the application of heat in this way has been carried far enough. It is very probable that if continued for longer periods, even at temperatures only a few degrees above that of blood heat, very serious results might take place.

After being subjected to this excessive heat, applied by means of water vapor, there is of course a tendency to reaction when the source of heat is withdrawn and the surface of the body is rubbed with cold water. The water which is first used for this purpose should be tepid, and gradually made cooler as the reaction takes place. The application of heat in the form of water is well shown, also, in its effects upon the excretory organs. The kidneys, especially, are stimulated and perform their functions more thoroughly when subjected to high temperatures applied in the manner described. Cold also may promote the secretion of urine by closing the pores of the skin.